i am presently revamping my "BuildyourownCNC machine". Plans from a book sold on the net. I want to use optical interupter switchs and need to know, how do you get the 5V to operate the IR transmitter and reciever. It works fine on a test board. when operating on the board I feed 5V in and get 5V out. When it is flagged the Votlage drops to 0V. Will I be using the 5V signal from the paralle port or do I have to set up a sperate 5V supply? My BOB is really basic BOB and my controllers are run with 12V. No actual power to the BOB other than the 5V (or nearly 5V) from the computer parallel port.

Being an optical switch you could get the 5v from your PC/BOB. It might not put out enough current but worth a try first. If not a wall wart or other externally supplied 5v source will be fine. Depending on the switch you use, they can require different voltages or a range. I use a proximity switch that will accept anything from 5-24v. Also the further away from 5v you can get on your signals, the less prone to noise your system will be.

Most phone chargers are 5v btw. Verify before using.

Thanks for the replies. I checked the output voltages from the computer and they run around 3 to 3.5 V. Wall Warts will be the best. I finally got my home made router table up and running last night. Had a problem with the Z axis not working, called my supplier and he gave me some suggestions but none worked. These are low end stepper motors and driver boards plus the BOB is very basic. Just the parallel input to screw termainals on the output side but they work. Everyone asks me what I am going to do with the router and all I can say is make wood dust. Oh, yeah, I found bad solder connections on the Z controller board and re soldered them and it worked. P.S. the phone wll warts are like $1.99 at Goodwill and there are tons of them hanging on pegs

If your output voltages are only 3-3.5v, chances are you will have issues. Most of the problems with laptops are due to this. My understanding is that the voltage differential isnt large enough to consistently trigger or activate. Everything I have read suggests 5v.

I finally went with the micor swtichs. I was having a problem with my system. I was going to change over to Linux EMC2 CNC program and it was on another computer. I hooked it up and guess I should have waited (to learn something about the Linux program first). Well when I switched back the comptures my Z axis would not work. I thought OH OH, I did something wong. I ended up ordereing another driver board from my supplier and installed it and nothing? I called my supplier and he suggested several things to try, nothing worked. I switched the stepper motor to another driver board and it worked OK. Hooked up the Y motor to the Z board and nothing. I thought heck, what am I going to do. So I started looking close at the old Z board and the new board I just got and it looked like several of the legs on some chips were not soldered to the board. There was solder on the underside and I would think the board would have Thru hole copper trace. Anyways, I went ahead and soldered where there didn't appear to have solder and by Golly It worked. I checked all the boards and every one is missing the solder on the top surface of these pins. I took all boards out and re soldered them all. If these boards have thru hole copper trace it is not working very good. How the other kept going is beyond me. I have another subject I need some help on but will post it later. Homing and jogging. Thanks for listening and the help.